Heat pump sizing guide

Our heat pump sizing guide shows what we refer to as the ‘ideal’ capacity to achieve your target temperature consistently, this ‘ideal’ capacity is calculated to allow for lower temperatures at the start and end of a swimming season and for cooler spells that naturally occur all year round given the UK weather.

When calculating our ideal capacity we consider several factors including whether it is an above ground or in-ground pool, the amount of insulation, whether the pool is covered when not in use, the expected swimming season, average air temperature and of course the target water temperature.

It is important to remember that the heating capacity required to achieve a water temperature of 28 degrees will vary according to changes in air temperature and the increased heat loss that occurs at cooler air temperatures or due to lack or insulation.

Whilst we assume an average air temperature of 15 degrees, our calculations actually factor in the reality that it could be 10 degrees one day and 20 degrees the next, therefore it should be remembered that capacities you see recommended elsewhere are probably based on consistent air temperature and therefore may appear less than our ideal capacities.

Not sure of your pool volume? Click here to use our calculators

Pool assumptions

  • Pools are outdoors and covered with suitable solar or bubble cover when not in use
  • May to September swimming season
  • Pool water temperature for swimming is 27-28°C
  • Average air temperature is 15°C

Pond assumptions

  • Ponds are outdoors and insulated and covered
  • Pond holding temperature 15°C in Winter / Summer 20-22°C

Insulation

  • Above-ground pools with a cover but no additional insulation are classed as ‘uninsulated’
  • In-ground pools with a cover, above ground pools that have been partially sunk into the ground or above ground pools with cover and additional side/base insulation are classed as ‘insulated’

Sizing guide

Uninsulated pool

Pool Volume (L)

Ideal Capacity (kW)
<10,000
 6kW
10-12,000
 7kW
13-15,000
 10kW
15-20,000
 13kW
20-30,000
 15kW
30-40,000
 18kW
40-50,000
 23kW
50-60,000
 26kW

Pool Volume (L)

Ideal Capacity (kW)
<15,000
 6kW
15-20,000
 8kW
20-30,000
 10kW
30-40,000
 13kW
40-50,000
 15kW
50-60,000
 18kW
70-80,000
 20kW
80-90,000
 23kW
90-100,000
 26kW
100-110,000
 29kW
110-120,000
 32kW

Pond Volume (L)

Ideal Capacity (kW)
<9,000
 9kW
9-12,000
 12kW
12-15,000
 15kW
15-19,000
 19kW
19-27,000
 27kW
>27,000
 Please call

Oversizing

To reach a higher water temperature a larger heat pump is recommended – you should look to increase capacity by approximately 2KW for each degree you want to raise the pool temperature above 27-28°C

  • If you need 6kW for 10,000L at 27-28°C, you would need 10kW for 30°C

    • To extend the swimming season a larger heat pump is recommended – you should look to increase capacity by approximately 3KW for each month before or after May to September

  • If you need 6kW for 10,000L, May to September, you would need 12kW for April to October

    • Heat Pump Sizing Form

    If you have an indoor pool, or would simply prefer us to size the heat pump required to heat your pool or pond, please complete the form below and we’ll be in touch shortly.

    The more information you can provide, the more accurate our recommendation.

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